1. Field of the Invention
The present invention concerns a method for mounting and dismounting a doctor blade chamber in a support holder on a printing unit, where the doctor blade chamber is placed in the support holder in a mounting position and subsequently is brought in contact with a roller, preferably an anilox roller, in a position of operation. The invention furthermore concerns an apparatus including a doctor blade chamber and a support holder on a printing unit, where the doctor blade chamber is provided with fixing means for fixing in the support holder in a mounting position and subsequently in a position of operation wherein the doctor blade chamber is in contact with a roller, preferably an anilox roller.
2. Description of Related Art
It is commonly known that in connection with printing units a so-called doctor blade chamber is used from which ink/glue/varnish is applied to a roller, typically an anilox roller. In the following the term “ink” will be used as an expression for the various media normally applied with a doctor blade chamber, why this term is to be construed broadly and not exclusively as ink in the actual sense. Moreover, the ink is transferred from the anilox roller to a printing cylinder on which an actual plate is mounted as the anilox roller is in contact with the printing cylinder. Between the printing cylinder and a counterpressure cylinder, the medium on which printing is performed is conducted, typically as a web. This printing method is commonly called flexo printing.
In principle, a doctor blade chamber is a container for ink upon which is mounted two doctor blades at an angle, and which by their free edges bear on the outer surface of the anilox roller. On the surface, the anilox roller is provided with a number of indentations called cups in which ink is received from the doctor blade chamber. The function of the doctor blades is to seal and to scrape excess ink off the surface of the anilox roller, respectively, such that ink is present in the cups in the surface of the roller and not in the areas between the cups. This type of doctor blade chambers are commonly known, and ink is supplied either via a pump at a suitable flow rate or as an ample amount, where additionally supplied either via a pump at a suitable flow rate or as an ample amount, where additionally there is an overflow by which excessively supplied ink is returned to a container. Alternatively, the doctor blade chamber is refilled manually with a pitcher or in other suitable ways, which is particularly advantageous in the production of small series.
In order for the doctor blade chamber to operate optimally, it is typically mounted at the side of the anilox roller at an angle of about 90° relative to vertical, and by change of ink or cleaning, the doctor blade chamber is pivoted about a horizontal axis such that the opening between the doctor blades face upwardly. Prior to this pivoting of the doctor blade chamber, the ink present in the doctor blade chamber may advantageously be emptied, as the ink otherwise will spill when the doctor blade chamber is pivoted out of its contact with the anilox roller. One way of preventing spilling is to empty the ink out through an overflow and subsequently pump flushing water through the doctor blade chamber before releasing it from the roller and turning it away from it.
This problem of unused ink to be emptied out of the doctor blade chamber or being wasted is attempted solved by a solution where a slide gate is inserted between the doctor blades and the surface of the anilox roller. By this solution, however, there is still a minor waste of ink, and at the same time it is necessary to adapt the printing unit such that there is less space for inserting this gate by sliding, which is to be inserted from the end of the roller and thus requiring free space in longitudinal direction of the roller corresponding to the length of the roller.
None of these methods are optimal, and they have several drawbacks as such process steps of emptying ink, flushing or inserting/sliding a gate is time-consuming and/or tedious, with a consequently more expensive process.